I have no idea but I feel for you - cankers are painful. I was told though that a sign it is crohn's related is the duration they stay and they come in clusters ~ where most people get rid of them in a couple of days and usually only get one.
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Hi Mayflower, I get Cankers all the time and I have never had them tested or is there such a test. They are ulcers and sometimes meds, teeth, or acidic foods can bring it on. When ever I am on Flagyl, almost guaranteed I get one, last week I got 2 at the same time, first time in over 30 years. Anyone know of such a test??? There are ways to help the pain when they do come but it crohns realated.

Okay, this might be a dumb question, but if you have an ulcer/canker sore in your mouth is there something they can do to test if it's Crohn's-related? Just curious. Thanks!

Never a dumb question. Oral aphthous ulcers, like the one in picture, can be associated with Crohns, as well as a broad range of other conditions. I've had them off and on going back to my 20's, though I haven't had any in quite awhile. Here's a good article on them Aphthous ulcer

I've gotten them for as long as I can remember. Usually one at a time, though, and I usually am guaranteed to accidentally bite it once or twice due to the swelling, which of course prolongs the agony.